2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/79457We study discrete, cocompact, isometric actions of groups on Hadamard spaces, and the induced actions on ideal boundaries. For a class of groups generalizing fundamental groups of three-dimensional graph manifolds, we find a set of invariants for the action which determine the boundary action up to equivariant homeomorphism. This work was inspired by (and answers) a question of Gromov from "Asymptotic invariants of infinite groups."Differential GeometryGroup Theory53C22 (Primary)text